Each statement has 2 unknowns. Represent both in terms of x. Q: The sum of two numbers is 35. Please explain and help.

The answer posted above uses two variables (unknowns), x
and y to represent the two terms. I am giving below a method of representing both the
terms using only one variable.

It is given that the sum of
two numbers is 35.

Let first term of the two be represented
by:

First term = x

We
know:

(First term) + ( Second term) =
35

Substituting the value x for first term in above
equation:

x + Second term =
35

Transferring x from left to the right hand side of
equation, which is same as subtracting x from both side of the
equation:

Second term = 35 -
x

Thus the two unknowns, the first term and the second term
are represented using just one (unknown) variable
'x'.

First term = x

Second
term = 35 - x

Please note that x, representing the first
term, can take any value, and based on value of x the value of second term will be
determined.